1. Field of the Invention
The present invention relates to a photoelectric conversion element unit used in an imaging apparatus, such as a digital camera and a video camera, and the imaging apparatus.
2. Description of the Related Art
When a photoelectric conversion element package is used in an imaging apparatus, it is necessary to align a light receiving surface of the photoelectric conversion element with an image forming surface of an imaging optical system with high accuracy. Therefore, a photoelectric conversion element package is fixed to a support plate whose external form is larger than the package, as is discussed in Japanese Patent Application Laid-Open No. 11-261904. Thus, an alignment of the support plate is performed so as to match a reception surface of a photoelectric conversion element with an image forming surface of an imaging optical system when the support plate is attached to a predetermined attachment point.
Japanese Patent Application Laid-Open No. 11-261904 discusses a method for reducing the total thickness of a photoelectric conversion element package, a support board and a printed wiring board where a photoelectric conversion element package is mounted since downsizing, and particularly a low-profile imaging apparatus. More specifically, a printed wiring board is arranged between a leadless type photoelectric conversion element package and a support board.
An imaging apparatus requires the aforementioned photoelectric conversion element package as well as a driving circuit that drives the photoelectric conversion element package, and a signal processing circuit that processes an output signal from the photoelectric conversion element. It is desirable that the driving circuit and the signal processing circuit are arranged as close as possible to the photoelectric conversion element to shorten the wiring length between them. This is because noise may likely be added to a minute analog signal output from the photoelectric conversion element when the wiring length becomes longer. Further, along with increased pixels and increased functions of the photoelectric conversion element, the speed of a driving clock of the photoelectric conversion element is enhanced. Under such a situation, a waveform of a signal driving the photoelectric conversion element may get out of shape due to the wiring length and an influence of a connector used for connecting the circuits, and the photoelectric conversion element cannot be properly driven. Furthermore, unnecessary radiation from the high speed clock lines may increase.
A driving circuit and a signal processing circuit are conventionally connected to the top of a flexible printed wiring board extracted from a photoelectric conversion element. In other words, a wiring length from the photoelectric conversion element to the driving circuit and the signal processing circuit has been long.